It is now said to be an age of electric motor vehicles. It is said that the electric motor vehicles will solve most of the environmental issues such as the exhaust gas from automobiles which is said to make up about 70% of air pollution, noises, or the like, and will extend the life of oil resources by two times or more.
Known electric motor vehicles are provided as their drive system with a battery, a motor, and a controller for controlling the speed of the motor, and a wheel is rotated by a drive transmission mechanism like conventional automobiles, or a wheel is rotated by a motor disposed on it without necessitating such a drive transmission mechanism like conventional automobiles. And, in developing an electric motor vehicle, the improvement of the performance of an onboard battery is an issue to be solved and it will not be long before it is solved.
Incidentally, the electric motor vehicle is also demanded to have its safety improved together with the improvement of its performance. A mere replacement of the drive motive power of a conventional gasoline automobile by a motor can not sufficiently provide the safety of the electric motor vehicle. Specifically, the electric motor vehicle uses electricity for a drive source, and the power is a motor which rotates at a high speed as compared with an engine. Therefore, a trouble of the electric system or a failure of the motor may suddenly stop a running vehicle or suddenly start a vehicle which was out of action. Besides, in common to a running vehicle and a stopping vehicle, there is a possibility that a driver or a mechanic may suffer from an electric shock, be caught by the drive unit in the vicinity of the motor, or break the motor or the controller when servicing. These troubles or the necessity of protection is caused due to the device or structure peculiar in the electric motor vehicle, which is not seen in conventional automobiles.
The inventors involved in the development of an electric motor vehicle propose the following points to prevent accidents or failures form occurring and to assure safety.
First point for safety: To avoid a travel motion trouble of the electric motor vehicle which may suddenly occur when traveling, for example, a sudden stop of the electric motor vehicle.
When the vehicle is exposed to wind and rain and suffers from vibration when traveling, water may enter the motor or the electric control circuit, causing an insulation failure (electrical short). This is very dangerous because it leads to a stop of the electrical motor vehicle. In this connection, the improvement of a stator fixing structure, a motor case structure will be proposed.